The Carolina Dog, a familiar-looking animal long known in the rural South as the "yaller dog," may be more than the common mutt that immediately meets the eye. I. Lehr Brisbin, Jr., Senior Ecologist at the University of Georgia's Savannah River Ecology Lab, believes that these animals may be America's most primitive dogs.

Brisbin's research is featured in a new television documentary Search for the First Dog, premiering in the United States tonight on the National Geographic Channel.

It was Brisbin's knowledge of Australia's dingo that first led him to look at a familiar local canine in an entirely new way.

Brisbin was studying the origins of the world's remaining wild, ancient dogs, including the dingo, which may have reached Australia walking alongside that continent's original human inhabitants thousands of years ago. Such primitive dogs are uncommon because the canine passion for choosing diverse mates often complicates breeding patterns.

Brisbin was struck by the physical appearance of an American wild dog that ended up in a pound near his South Carolina home. "You look like a dingo," he thought in a moment of revelation, "I wonder how many of you other guys are out there that look like dingos?"

The answer: possibly quite a few, but only in selected places. Although their wild numbers seem to be rapidly decreasing, Brisbin located a number of these animals in secluded areas far from the presence of humans or domestic dogs. Their appearance first led him to propose his theory of their ancient originsthey could have arrived in America along with the earliest migrating humans across the Bering Strait land bridge. If so, Carolina Dogs could be among the earliest dogs to enter North America many thousands of years ago.

Behavior, DNA Suggest Uncommon Background

The exciting idea remains a hypothesis, one that's under examination by an analysis of fossils, cave paintings, and other pieces of the North American historical record. Early paintings of Native Americans, for example, show accompanying dogs whose appearance looks strikingly like today's Carolina Dogs.

Another suggestive piece of evidence is comparison with dogs that remain on the other side of the long vanished Asia-North America land connection.